Barium oxide

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Barium oxide
NaCl polyhedra.png
Identifiers
CAS number 1304-28-5 YesY
PubChem 62392
ChemSpider 56180 YesY
RTECS number CQ9800000
Jmol-3D images Image 1
Properties
Molecular formula BaO
Molar mass 153.326 g/mol
Appearance white solid
Density 5.72 g/cm3, solid
Melting point 1923 °C
Boiling point ~2000 °C
Solubility in water 3.48 g/100 mL (20 °C)
90.8 g/100 mL (100 °C)
Solubility soluble in ethanol, dilute mineral acids and alkalies; insoluble in acetone and liquid ammonia
Structure
Crystal structure cubic, cF8
Space group Fm3m, No. 225
Coordination
geometry
Octahedral
Thermochemistry
Std molar
entropy
So298
70 J·mol−1·K−1[1]
Std enthalpy of
formation
ΔfHo298
−582 kJ·mol−1[2]
Hazards
MSDS External MSDS
EU Index 056-002-00-7
EU classification Harmful (Xn)
R-phrases R20/22
S-phrases (S2), S28
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other anions Barium hydroxide
Barium peroxide
Other cations Calcium oxide
Strontium oxide
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Barium oxide, BaO, is a white hygroscopic non-flammable compound. It has a cubical structure. It is used in cathode ray tubes, making crown glass. It is a harmful to human skin and if swallowed in large quantity causes irritation. Excessive quantities of barium oxide may lead to death.

It is prepared by heating barium carbonate with coke, carbon black or tar or by thermal decomposition of Barium nitrate.


Uses[edit]

Barium oxide is used as a coating for hot cathodes, for example, those in cathode ray tubes. It replaced lead(II) oxide in the production of certain kinds of glass such as optical crown glass. While lead oxide raised the refractive index, it also raised the dispersive power, which barium oxide does not alter.[3] Barium oxide also has use as an ethoxylation catalyst in the reaction of ethylene oxide and alcohols, which takes place between 150 and 200°C.[4]

It is also a source of pure oxygen through heat fluctuation. It readily oxidises to BaO1+x by formation of a peroxide ion. The complete peroxidation of BaO to BaO2 occurs at moderate temperatures but the increased entropy of the O2 molecule at high temperatures means that BaO2 decomposes to O2 and BaO at 1175K.[5]

Preparation[edit]

Barium oxide is made by heating barium carbonate with coke, carbon black or tar. It may also be prepared by thermal decomposition of barium nitrate.[6] Likewise, it is often formed through the decomposition of other barium salts.[7]

2Ba + O2 → 2BaO
BaCO3 → BaO + CO2

Safety issues[edit]

Barium oxide is an irritant. If it contacts the skin or the eyes or is inhaled it causes pain and redness. However, it is more dangerous when ingested. It can cause nausea and diarrhea, muscle paralysis, cardiac arrhythmia, and can cause death. If ingested, medical attention should be sought immediately.

Barium oxide should not be released environmentally; it is harmful to aquatic organisms.[8]

See Also[edit]

References[edit]

  1. ^ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X. 
  2. ^ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X. 
  3. ^ "Barium Oxide (chemical compound)". Encyclopædia Britanica. Encyclopædia Britanica. 2007. Retrieved 2007-02-19. 
  4. ^ Nield, Gerald; Washecheck, Paul; Yang, Kang (05-04). "United States Patent 4210764". Retrieved 2007-02-20. 
  5. ^ S.C. Middleburgh, K.P.D. Lagerlof, R.W. Grimes - Accommodation of Excess Oxygen in Group II Oxides http://onlinelibrary.wiley.com/doi/10.1111/j.1551-2916.2012.05452.x/pdf
  6. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  7. ^ "Compounds of barium: barium (II) oxide". Web Elements. The University of Sheffield. 2007-01-26. Retrieved 2007-02-22. 
  8. ^ "Barium Oxide (ICSC)". IPCS. October 1999. Archived from the original on 26 February 2007. Retrieved 2007-02-19. 

External links[edit]